The present disclosure relates to transistors, and more specifically, to methods that utilize self-alignment processes and epitaxial growth processes (and the resulting structures).
A bipolar junction transistor (BJT or bipolar transistor) is a type of transistor that relies on the contact of two types of semiconductor for its operation. One type of semiconductor is formed with positive-type dopants, and is therefore referred to as a P-type semiconductor; while another type of semiconductor is formed with negative-type dopants, and is therefore referred to as an N-type semiconductor. Bipolar junction transistors can be used as amplifiers, switches, or in oscillators. Bipolar junction transistors come in two types, or polarities, known as PNP and NPN, with the P and the N representing the different doping types of the three main terminal regions (collector, base, and emitter). An NPN transistor comprises two semiconductor junctions that share a thin P-doped anode region, and a PNP transistor comprises two semiconductor junctions that share a thin N-doped cathode region.